Multiplexing technique for quasi-distributed sensors arrays in polymer optical fiber intensity variation-based sensors

This paper presents a multiplexing technique for polymer optical fiber (POF) intensity variation-based sensors. The technique relies on the side-coupling between the light source and the POF lateral section. Thus, each sensor has its own light source which has its activation as well as its signal acquisition (made with two photodetectors, one at each end of the POF) controlled by a microcontroller. With this technique, a matrix with the number of columns equal to the number of photodetectors multiplied by the number of light sources (or sensors) is obtained. This enables the decoupling of the response of each sensor. The presented analytical approach shows a tradeoff between the number of sensors and their sensitivities (considering the dynamic range of each sensor). In addition, experimental results show the feasibility of the technique to measure angles in a 3 degrees-of-freedom (DOF) systems with errors as low as 3 degrees. Furthermore, the proposed approach was also tested in multi-parameter applications, where temperature, angle and force were estimated with errors up to 5% with an array with 3 POF sensors. The results presented in this paper can pave the way for novel applications of quasi-distributed sensors with intensity variation-based sensors both in multi-DOF systems and in multi-parameter applications with the additional advantages of lower cost than fiber Bragg gratings-based systems and lower spatial resolution than distributed sensors.